GONIODORIS. 



Fig.^ 9. General view of the viscera of Polycera quadrilineata, the dorsal skin being laid open and the 

 various organs a little separated : — a, buccal mass ; b, salivary glands ; c, oesophagus ; d, 

 upper wall of stomach ■ e, intestine ; /, vent ; g, liver mass enveloped in the ovary ; h, 

 retracted penis ; i, glandular portion of testis ; i, tubular portion of the same ; i" , constricted 

 tubular portion ; i" , short tube uniting the glandular portion to the oviduct ; j, oviduct as it 

 leaves the ovary ; /, dilated portion of the same ; k, mucus-gland in connexion with female 

 parts ; /, vaginal tube leading from the exterior of the spermatheca ; m, spermatheca ; n, tube 

 from the same to the oviduct ; o, accessory spermatheca j p, ventricle of the hearty turned 

 forward ; q, a portion of the auricle ; r, arterial trunks ; s, cerebral ganglia ; t, branchial 

 plumes. 



10. External view of one of the jaws of Polycera quadrilineata : — a, cutting edge ; b, upper 

 margin. 



11. Jaws of Polycera Lessonii, as seen in the compressor of the microscope, the buccal mass laid 

 open from below : — a, buccal lip ; b, jaws ; c, point of articulation ; d, cutting edge. 



12. Cerebral ganglions of Polycera quadrilineata : — a, a, cerebroid ganglions ; b, b, branchial ; c, c, 

 pedial ; d, olfactory ; e, visceral ; /, buccal ; g, g, commissural cords connecting the buccal 

 ganglions to the cerebroids ; h, small collar uniting the branchial and visceral ganglions ; i, 

 great oesophageal collar ; I, olfactory nerves terminating in ganglionic enlargements {j ) 

 within the tentacles ; 2 } nerves to the oral tentacles ; 3 and 4, those to the channel of the 

 mouth ; 5, optic nerves, each having at its origin a small ganglion ; 6, nerves supplying 

 tentacular filaments and dorsal skin in front ; 7, pallial nerves ; 8, a nerve to the skin on the 

 side of the body; 9, 10, 11, pedial nerves; 12, 13, buccal nerves; 14, lingual nerves; 15, 

 oesophageal nerves ; 16, 17, 18 visceral nerves. 



13. Buccal mass of Mgirus punctilucens, side view : — a, channel of the mouth ; b, oesophagus ■ 

 c, lingual sheath ; d, d, salivary glands ; e, glandular organ, supposed for secreting mucus to 

 lubricate the foot. 



14. Front view of buccal mass of the same, the channel of the mouth having been removed : — 

 a, buccal lip ; b, oral opening ; c, lingual sheath ; d, upper corneous jaw, or tooth ; e, lateral 

 membranous fringes. 



15. Corneous jaw or tooth of Mgirus punctilucens removed from the buccal lip : — a, cutting edge 

 with median denticle. 



